Traditionally,
the first Germanic military force arrived in Britain in around 440 CE to serve as mercenary troops at
the invitation of the British sub-Roman government. Glidas
records that Celtic leader Vortigern wished to use
them against the Picts.

When the
government failed in their agreement to supply them, thesetroops
revolted. This revolt touched a significant part of the country. Then, the
first settlers invited their relatives from overseas to join them. At the beginning
of the sixth century, the Germanic peoples rapid spread through the country was
checked for a time by the British, but by the mid sixth century they started to
expand again. By the time of Augustine's arrival, they controlled much of the
lowlands and were expanding to the north and west.

The Celtic
peoples used the name "Saxon" generically to describe all of the Germanic
people with whom they came into conflict. While this likely indicates a heavy
proportion of Saxons in the early raids and settlement, many other tribes were
involved. Significantly, Britain came to be called England after the Angles rather than the Saxons.

Gildaswritng in 540 CE
described the breakdown of order after the withdrawal of Roman forces. Scots
and Picts on the former frontier raided in Britain and the people were unable to control them. An
appeal for aid was sent to Aetius in Gaul,
but the Romans were too busy with troubles of their own and were unable to
help.

The British
leader Vortigern whom Gildas
called a "proud tyrant", arranged for a Saxon warband
under Hengest and Horsa to
settle in the country as federates for protection against the Scots and Picts.

Nennius writing in 800 CE implies that the
government officials who hired the Saxons not only feared the Scots and Picts, but also the Romans in Gaul and Ambrosius
in Britain. If Vortigern, the proud
tyrant, was a leader of the Pelagian party in
Britain, that fear would be understandable.

When hard times
came and the government was not able to meet its obligations to the Saxons,
they revolted and ravaged the countryside. Under the leadership of AmbrosiusAurelianus, the British
eventually fought back and reached a stalemate after a battle at MonsBadonicus which
resulted in a generation of peace.

Ambrosius' likely power base was Wiltshire where the
place-name Amesbury suggests "stronghold of Ambrosius".
At the time Gildas was writing in the 540s, he felt that
this peace was threatened. The capture of Old Sarum
by Wessex in 552 may have ended Gildas'
period of peace.

Continental
evidence suggests a reverse migration of Germanic people out of Britain during this time. Also notably, there is no
activity in Kent from 473 until 565 in the Anglo-Saxon Chronicle.

Gildas made no mention of the British hero Arthur. Since
his battles are reputed to have taken place during this time, Gildas should not have ignored him if he had been as famous
as indicated by Nennius and later Gregory of
Monmouth.

The legends of
Arthur appear to have developed out of late Welsh legends that suggest a
British commander called Artorius won some repute
against the Saxons